Most spark-ignited internal combustion engines used in automotive vehicles have employed fuel systems with either a carburetor, or more recently, multiple fuel injectors mounted in an intake manifold or within individual intake ports. Each of these systems provides fuel to the engine via the intake manifold. Although manifold/port mounted fuel injectors have generally been satisfactory, and indeed, a great improvement as compared with carburetor systems, automotive designers are increasingly moving to the use of direct fuel injection with spark-ignited engines. With a direct injection system, fuel injectors are typically mounted through the fire deck of the engine's cylinder head and provide fuel directly into each of the engine's combustion chambers.
In spark ignition engines, direct injection has been found to be beneficial in terms of improved fuel economy, coupled with reduced exhaust emissions. Although direct injection has been used in many types of diesel engines for years, this new application of direct injection, particularly in gasoline engines intended for use in automotive vehicles, has created a problem because the higher pressures utilized with direct injection have caused unwanted noise or “tick” while the engine is idling; under certain cases the tick may become more pronounced at high speeds and loads. This tick noise, resulting from injector needle impact, has not generally been a problem with most diesel engines, but has definitely proved to be an issue with direct-injected spark ignited engines used in automobiles, as well as with some diesel engines.
It would be desirable to provide a system allowing a low noise signature for gasoline and diesel direct injection fuel systems at lower loads, including idle, while at the same time preserving the durability of fuel injectors by preventing unwanted injector movement during higher load operation. This presents a challenge, because if, without anything more, the injector's mounting is softened to the point where ticking noise is attenuated at idle, the corresponding axial movement of the injector within the cylinder head's injector pocket at high loads may cause adverse durability affects upon injector tip seals.